Tim Bray:

Tablets and handsets can displace computers as play and reading devices, but they really can’t become dominant as work tools until we have a better solution for high-speed low-friction text input. On the other hand, I wouldn’t be surprised to see dramatic progress in this area; it’s so obviously the number-one usability barrier for everything that isn’t badged as a “computer”.

Agreed — though I don’t agree with much else in his post. Reviewers take note: you need to dedicate at least 250 words to talking about how the text input experience is on each device you review — this stuff matters.